The electrochemical fuel cell is not new. Invented in 1839 by Alexander Grove, it has recently been the subject of extensive development. NASA used its principals in their 1960""s space program, but the latest push into this technology is being driven largely by the automotive industry. Daimler-Chrysler and Ford Motor Co. together have invested about $750 million in a partnership to develop fuel cell systems. As environmental concerns mount and legislation toughens, development of xe2x80x9cgreenxe2x80x9d energy sources becomes more justified as a course of action, if not required.
The information age has ushered in the necessity for new ways to examine, process, manage, access and control the information. As the basic technologies and equipment evolve to handle these new requirements, there is a growing need for a smaller, lighter and faster (to refuel/recharge) electrical energy source. Portable computing and communications, in particular, would benefit greatly from a miniature fuel cell based power source.
In accordance with the invention, a method and apparatus is provided which uses a combination of SAMs (self-assembled monolayers), MEMS (micro electrical mechanical systems), xe2x80x9cchemistry-on-a-chipxe2x80x9d and semiconductor fabrication techniques to create a scalable array of power cells directly on a substrate, preferably a semiconductor wafer. These wafers may be xe2x80x9cstackedxe2x80x9d (i.e. electrically connected in series or parallel, as well as individually programmed to achieve various power (V*I) characteristics and application driven configurations.
One preferred embodiment of the invention is formed by fabricating a plurality of individual fuel cells on a planar semiconductor wafer into which flow channels are formed by etching or other well-known semiconductor processes. Oxygen is admitted into one side of a channel and hydrogen into the other side; with the two gases being separated by a membrane. Electrodes are formed on opposite sides of the membrane and a catalyst is provided in electrical communication with the electrode and membrane on both sides. Lastly, a gas impermeable cover or lid is attached to the cell.
Preferably, the membrane is a PEM (Proton Exchange Membrane) formed by depositing or otherwise layering a column of polymers into etched channels in the substrate to create a gas tight barrier between the oxygen and hydrogen, which is capable of conveying hydrogen ions formed by the catalyst across the barrier to produce electricity across the contacts and water when the H-ions combine with the oxygen in the other channel.
In addition, a number of fuel cells can be electrically interconnected and coupled to gas sources on a portion of the same wafer to form a xe2x80x9cpower chipxe2x80x9d. Traditional electrical circuitry can be integrated on the wafer along with the chips to provide process monitoring and control functions for the individual cells. Wafers containing multiple chips (power discs) or multiple cells can then be vertically stacked upon one another.
A further understanding of the nature and advantages of the invention herein may be realized with respect to the detailed description which follows and the drawings described below.